docs: def list_images(self):
          """
          list all available nspawn images
  
          :return: collection of instances of :class:`conu.backend.nspawn.image.NspawnImage`
          """
          # Fedora-Cloud-Base-27-1.6.x86_64 raw  no  601.7M Sun 2017-11-05 08:30:10 CET \
          #   Sun 2017-11-05 08:30:10 CET
          data = os.listdir(CONU_IMAGES_STORE)
          output = []
          for name in data:
              output.append(self.ImageClass(name, pull_policy=ImagePullPolicy.NEVER))
          return output